The invention relates to a motor vehicle with at least a battery module having a cooling system.
Electric mobility is becoming increasingly important in particular from an environmental point. While purely electric vehicles still play a minor role and are particularly suitable for transport in inner cities, hybrid vehicles, especially mild-hybrid vehicles, become increasingly common.
In typical hybrid vehicles, a combustion engine and an electric motor are used. The electric propulsion portion is merely supportive in a mild-hybrid, i.e. it is used to improve the performance of the vehicle. In addition, fuel can be saved especially when starting or accelerating. The batteries are here charged mainly by recovered energy, for example by braking.
Especially in a mild-hybrid, batteries can be charged or discharged very quickly. Because each battery has an internal resistance, this causes heating of the battery. However, high temperatures may reduce the lifetime of the batteries. In addition, it may be necessary to limit the charging and discharging rate in order to avoid overheating of the battery. Therefore, such a battery module is advantageously cooled.
The document DE 103 37 493 A1 discloses a method and an apparatus for cooling a vehicle battery. The battery is placed in a container which is substantially sealed except for a cooling air inlet and an air discharge opening. An air nozzle is provided which deflects the relatively cool air from the outside of the vehicle to the cooling air inlet. Air then flows past the battery, cooling the battery. However, only a limited cooling performance can be achieved with cooling based solely on ambient air.
DE 10 2008 01 1466 A1 discloses a battery module, which is cooled by a compressed refrigerant fluid, specifically air. The use of compressed air provides two advantages. On the one hand, this air has more mass per unit volume, which increases the cooling capacity. On the other hand, the battery module may include an expansion element, providing cooling through expansion. However, the air is heated by the compression, which adversely reduces the cooling performance. This is avoided in that the compressed air is cooled between the compressor and the battery module. A chiller is proposed for cooling. However, such a cooling arrangement consumes a substantial amount of energy.